| 1950 |
Nihon Eisai Co., Ltd.'s contraceptive suppository : Sampoon : , researched and developed during Japan's postwar baby boom, receives official approval from the Japanese government. |
| 1950 |
Nihon Eisai Co., Ltd. launches cardiotonic : Neophyllin : in Japan. |
| 1952 |
Nihon Eisai Co., Ltd. launches high-dosage vitamin B1 and B2 product : Chocola BB Tablets : in Japan. |
| 1952 |
Nihon Eisai Co., Ltd. launches motion sickness remedy : Travelmin : in Japan. |
| 1955 |
The company changes its name from Nihon Eisai Co., Ltd. to Eisai Co., Ltd., as it is known today. |
| 1957 |
Eisai rolls out its first three-year mid-term plan. |
| 1957 |
Eisai's Head Office building is completed in Tokyo. |
| 1961 |
Eisai opens its Taipei Office (now part of Eisai Taiwan Inc.), the company's first overseas branch, in Taiwan. |
| 1961 |
Eisai is publicly listed in the First Section of both the Tokyo and Osaka Stock Exchanges. |
| 1961 |
Gastrointestinal remedies : Saclon : and : Saclon Tablets : , recognizable for their distinct green hue even today, are launched in Japan. |
| 1964 |
Toyoji Naito receives the Japan Marketing Award, which recognizes people who have made a significant contribution to marketing and advertising in Japan. |
| 1964 |
The Tokyo Olympics take place. |
| 1966 |
The Kawashima Plant is completed in Gifu, central Japan. |
| 1966 |
Kawashima Plant opening ceremony. |
| 1966 |
Founder Toyoji Naito is appointed as chairman and Yuji Naito as company president. A three-tier representative director system is introduced: Chairman Toyoji Naito, President Yuji Naito, and Executive Vice President Tatsuo Naito. |
| 1969 |
Youda Co., Ltd. is established as a pharmaceutical imports subsidiary in Taiwan. |
| 1970 |
PT Eisai Indonesia is established as a pharmaceutical manufacturing and sales subsidiary in Indonesia. |
| 1970 |
Toyoji Naito resigns as representative director and chairman to assume director and honorary chairman roles. |
| 1971 |
Toyoji opens the Naito Museum of Pharmaceutical Science and Industry, Japan's first pharmaceutical museum, in Gifu. |
| 1973 |
The first oil crisis occurs due to conflict in the Middle East. |
| 1974 |
Eisai (Malaysia) Sdn. Bhd. and Hi-Eisai Pharmaceutical Inc. are established as pharmaceutical sales subsidiaries in Malaysia and the Philippines, respectively. |
| 1974 |
Metabolic cardiotonic : Neuquinon : is launched in Japan. |
| 1977 |
Naturally derived vitamin E product : Juvelux : is launched in Japan. |
| 1978 |
Eisai's founder Toyoji Naito passes away at age 89. |
| 1978 |
Peripheral neuropathy treatment : Methycobal : is launched in Japan. |
| 1979 |
Eisai Asia Regional Services Pte. Ltd. is established as a sales support and management services subsidiary in Singapore. |
| 1979 |
The second oil crisis erupts due to the Iranian Revolution. |
| 1991 |
The Beijing Representative Office is established in Beijing, China. |
| 1991 |
Shenyang Eisai Pharmaceutical Co., Ltd. is established as a Chinese–foreign contractual joint venture in pharmaceutical manufacturing and sales in Shenyang, China. |
| 1996 |
Eisai Suzhou Pharmaceutical Co., Ltd. is established as a pharmaceutical manufacturing and sales subsidiary in Jiangsu, China. |
