There was a by-election for the United Kingdom House of Commons in Hamilton on Wednesday 31 May 1978. It was caused by the death of the incumbent Labour Party Member of Parliament Alex Wilson on 23 March of that year. As the opening game of the 1978 FIFA World Cup was on Thursday 1 June, the by-election was held one day earlier, on the Wednesday. All by-elections since then have been held on a Thursday. The Labour candidate was George Robertson, who defeated SNP candidate Margo MacDonald, with an increased majority.