Internationally co-authored publications may be regarded as an indicator of scientific cooperation between countries and is of interest in science policy. In this study, the extent of international collaboration in Indian science has bean estimated from SCI data in 1990 and 1994. We find an increase in collaboration both in terms of output and the extent of the network and significantly higher impact (IF) associated with internationally co-authored papers in several disciplines. However, there was no significant increase in IF of collaborative papers over time, whereas Indian papers in general showed a statistically significant, though small, increase in average impact from 1990 to 1994. The bulk of Indian scientific co-operation was with the developed Western nations and Japan, but it was often the smaller countries with a few coauthored papers which showed higher average impact. Go-operation with South Asian countries, initially low, has doubled in four years. By a combination of multivariate data analysis techniques the relative positions of India's partners in scientific collaboration have been mapped with respect to the fields of co-operation.