
Kaspersky's then-future wife Natalya Kaspersky became his coworker at KAMI. It earned about $100 per month, mostly from companies in Ukraine and Russia. At first the software was purchased by about ten clients per month. There, he and his colleagues improved the software and released it as a product called Antiviral Toolkit Pro in 1992. In 1991, Kaspersky was granted an early release from his military service and left the defense ministry to take a job at the Information Technology Center of a private company KAMI, in order to work on his antivirus product full-time. Early on Kaspersky's anti-virus software had just 40 virus definitions and was distributed mostly to friends. Afterwards he continually found new viruses and developed software to remove them, as a hobby.

He studied how the virus worked and developed a program to remove it.

Kaspersky's interest in IT security began in 1989, when his PC was infected by the Cascade virus, while working for the Ministry of Defence.
