International Biotechnology Trust's net asset value per ordinary share rose from 575.1p to 656.7p in the six months to the end of February.
The company said this included a currency gain of £11.6m, equivalent to 30.9p per share.
The NAV per share returned 16.2% including the first dividend payment of 11.5p per share, which was announced in December.
It said that over the same period, the ordinary share price of the company increased by 21.1%.
This compared to a rise in the NASDAQ Biotechnology Index of 12.2% and a gain in the FTSE All-Share Index of 8.6%.