Aims: Observed changes in subcategories of injury death were used to test the hypothesis that a sizeable proportion of ''injury deaths of undetermined intent'' (Y10-Y34 in ICD 10) in the Baltic and Slavic countries after the USSR dissolved in 1991 were hidden suicides.
Methods: Using male age-adjusted suicide rates for two distinctly different periods, 1981-90 and 1992-2005, changes, ratios and correlations were calculated. The data were compared with the EU average.
Results: After the USSR broke up, the obligation to make a definitive diagnosis became less strict. A massive increase in ''injury deaths of undetermined intent'' resulted. The mean rate for the second period reached 52.8 per 100,000 males in Russia (the highest rate) and 12.9 in Lithuania (the lowest), against 3.2 in EU-15. The rise from the first to the second period was highest in Belarus (56%) and Russia (44%). The number of injury deaths of undetermined intent was almost equal to that of suicides in Russia in 2005 (ratio 1.0) and Ukraine in 2002 (1.1). In all the countries, especially the Slavic ones, prevalence trends of injury-death subcategories were uniform, i.e. strongly correlated over time. No direct substitution of one diagnosis for another was evident.
Conclusions: There is no evidence that the category of ''injury deaths of undetermined intent'' in the Baltic and Slavic countries hides suicides alone. Aggregate level analysis indicates that accidents and homicides could sometimes be diagnosed as undetermined.