IF EXISTS (SELECT 1 FROM sysobjects WHERE name = 'ProcName' AND TYPE = 'P')
    DROP PROCEDURE ProcName
go

CREATE PROCEDURE ProcName
AS
BEGIN
.... content
END
go

GRANT EXECUTE ON ProcName TO PUBLIC
go

/* test */

if exists (select 1 from sysobjects where name = 'ProcName' and type = 'P')
    drop procedure ProcName
go

create procedure ProcName
as
begin
	select 1
end 
go

grant execute on ProcName to public
go

select 1 from sysobjects where name = 'ProcName' and type = 'P'
go

Group Execution

/* test */

if exists (select 1 from sysobjects where name = 'ProcName' and type = 'P')
    drop procedure ProcName
create procedure ProcName
as
begin
	select 1
end
grant execute on ProcName to public
select 1 from sysobjects where name = 'ProcName' and type = 'P'


Elapsed Time:  0 hr, 0 min, 0 sec, 23 ms.

if exists (select 1 from sysobjects where name = 'ProcName' and type = 'P')
    select 1
go

select 2
go

select 1 from sysobjects where name = 'ProcName' and type = 'P'
go

select 3
go

1> if exists (select 1 from sysobjects where name = 'ProcName' and type = 'P')
2>     select 1
3> go
4> select 2
5> go
 
 -
 2
(1 row affected)
1> select 1 from sysobjects where name = 'ProcName' and type = 'P'
2> go
 
 
(0 rows affected)
1> select 3
2> go
 
 -
 3
(1 row affected)
 
 -
 3
(1 row affected)
1> Elapsed Time:  0 hr, 0 min, 0 sec, 4 ms.
2> go