The satellite broadcaster added just 40,000 new subscribers in the first three months of year, despite increasing its marketing spend by £26 million over the period. It now has 8.1 million subscribers.
However, the company announced that 149,000 new customers had signed up to its personal video recorder service, Sky+, in the same period.
The broadcaster said this week it would add a further 60,000 new customers in the three months to June and confirmed that HDTV would launch on 22 May.
Sky increased its revenue by 9 per cent to £3.079 billion. Operating profit increased by 15 per cent to £660 million.
James Murdoch, the chief executive of Sky, said: "Our focus during the quarter was to successfully implement our new customer management systems, complete preparations for the launch of Sky HD, and continue to ready the business for the launch of residential broadband services in the summer."