Cervico-isthmial incompetence develops in the second trimester of pregnancy. There are problems as to the correct treatment. The authors report four cases where stitches were put in late using the technique of "parachute" cerclage. This made it possible for four live babies to be born. A search of the literature shows that after late cerclage in 60-90% of cases pregnancy continues normally. But it has to be realised that complications do occur and these are mainly chorio-amnionitis which carries a bad prognosis obstetrically and also premature rupture of the membranes. The authors recommend this manoeuvre in spite of the risks because of the benefits that can be obtained. The procedure should only be carried out if there is no cervico-vaginal infection as determined by negative swabs and tocolytic treatment should also be given.